1. Field of the Invention
The present invention relates generally to toilet fill valves and particularly to shank assemblies for such toilet fill valves.
2. Description of Prior Art and Related Information
A toilet tank typically employs plug and flapper tank valve that is levered open, which remains open while a full tank is emptied. A fill valve provides water from a supply line to the toilet tank. The fill valve is open whenever the water level in the tank is below a predetermined level. Efforts have been spent reducing the noise when water refills the tank through the fill valve.
A fill valve typically includes a shank assembly. The core of the conventional shank assembly is a unitarily formed, complex piece having an inner cylinder and an outer cylinder. A water path is formed between the inner cylinder and the outer cylinder.
Molding the complex core as a single piece including the unitarily formed inner and outer cylinders poses major challenges. The molds need to have large sizes in order to accommodate the complex features of the core of the conventional shank assembly. The geometry of the conventional shank assembly creates areas where the only way to mold the complex core is to have thick sections of plastic material. The thick sections are subject to voids and stress that weaken the structure of the valve. The thick sections of plastic also cause the cycle time to be long. The weak areas of the complex piece, combined with the difficult “core pull” process, limit the choice of suitable materials for molding the shank conventionally.
The complex structure of the core of the conventional shank assembly also causes problems when the automated assembly process is adopted. To solve this problem, an additional component, i.e., a positioner, is included in the conventional shank assembly for the sole purpose of aiding the assembly process.
A third component of the conventional shank assembly, i.e., an O-ring, is used to seal a gap between the shank and a valve body, which partially covers the shank. However, fitting the O-ring in the gap between the shank and the valve body is a difficult process.
When the fill valve is hand assembled in small quantities, the conventional shank assembly does not cause many problems. However, in automated assembling process, aligning the parts and installing the O-rings become problematic.